rustgym 0.2.0

struct Solution;

use std::collections::HashMap;

impl Solution {
    fn roman_to_int(s: String) -> i32 {
        let map: HashMap<char, i32> = vec![
            ('I', 1),
            ('V', 5),
            ('X', 10),
            ('L', 50),
            ('C', 100),
            ('D', 500),
            ('M', 1000),
        ]
        .into_iter()
        .collect();
        let mut sum = 0;
        let mut last = 0;
        for c in s.chars() {
            if let Some(&v) = map.get(&c) {
                if v > last {
                    sum += v - last - last;
                } else {
                    sum += v
                }
                last = v;
            }
        }
        sum
    }
}

#[test]
fn test() {
    assert_eq!(Solution::roman_to_int(String::from("III")), 3);
    assert_eq!(Solution::roman_to_int(String::from("IV")), 4);
    assert_eq!(Solution::roman_to_int(String::from("IX")), 9);
    assert_eq!(Solution::roman_to_int(String::from("LVIII")), 58);
    assert_eq!(Solution::roman_to_int(String::from("MCMXCIV")), 1994);
}